Bi-directional hot box detector



United States Patent C 1 2,999,151 BI-DIRECTIONAL HOT BOX DETECTOR Bernard Rosett, Forest Hiiis, N.Y., assignor to Servo "Corporation of America, New Hyde Park, N.Y., a

corporation of New York Filed Aug. 6, 19 57, Ser. No. 676,646 I'Claim. (Cl. 246-469) My invention relates to an improved hot-box detector 'of the variety which is mounted alongside a railway track and which automatically and remotely responds to the passage of an overheated journal box. This application incorporates improvements over the disclosures of copending patent applications Serial No. 506,125, filed May 5, 1955, in the name of Sabert N. Howell, and Serial No. 620,703, filed November 6, 1956, in the names of Cornelius A. Gallagher and William M. Pelino, both applications now abandoned.

It is an object of the invention to provide an proved hot-box detector construction.

It is another object to meet the above object with a device which is bi-directionally responsive to passing railroad traflic, that is, which responds to detected hotboxes regardless of the direction of trafiic on a section of track being monitored and which in every case re- 'sponds with the same viewing aspect regardless of the direction of trafiic; in other words, for example, regardless of the direction of trafiic, the viewing aspect may always be on the trailing or rear side of ,passing journal boxes.

It is a specific object to provide a bi-directional hotbox detector utilizing the same heat-responsive cell means and electronic signal-processing circuitry, regardless of the direction of trafiic.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification, in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

FIG. 1 is a fragmentary view in perspective, showing a section of track to which my detector has been applied, and showing the general geometry of the detector optics, with respect to the journal box of a piece of passing rolling stock;

FIG. 2 is a View on a reduced scale showing a side or axial-end elevation of the arrangement of FIG. .1;

FIG. 3 is a diagram schematically depicting electrical and optical parts of the detector of FIG. 1; and

FIG. 4 is a simplified diagram illustrating a special purpose wheel trip, for use as an alternative :to the Whgel-trip means discussed in connection with FIGS. 1 t

Briefly stated, the invention contemplates an improved hot-box detector of the varietyin which a heat-responsive cell or element is fixedly mounted alongside a section of track to be monitored. Optics continuously image the cell in the general horizontal plane of passing journal boxes and on an axis inclined generally upwardly from beneath the passing boxes. The vertical plane which includes the viewing axis is preferably substantially, although not necessarily strictly, parallel to the track, so that the viewing of brake shoes, steam-hose connections and the like can be substantially avoided, and so that the primary background (as far as the cell-viewing aspect is concerned) may be the underside of the floor or base platform for each of the passing cars.

In the particular form to be described, a single heatresponsive cell serves each of two oppositely diverging viewing aspects, each viewing aspect being served by a "separate optical system and by a separate mechanical shutter for protecting the optical systems. Novel trip assalsi and gating means are described whereby, depending upon the direction of passing railroad traffic, not only is the correct viewing axis selected automatically to the exclusion of the other viewing axis, but heat signals from the region of prime interest on each passing journal box are monitored to the exclusion of other possible signals, for deviation from normal temperature.

Referring to FIGS. 1, 2 and '3 of the drawings, the invention is shown in application to a detector unit contained within a housing 10 permanently mounted, as by means securing the same to adjacent cross-ties 12 supporting a section of track 13. The housing It may contain a low-heat responsive or far-infrared detecting cell 14 (FIG. '3), such as a thermistor flake, and optics such as an infrared-transmitting lens 15 imaging the cell 14 along an axis 16, as at the location 17 in the general horizontal plane of passing journal boxes 18. The detector 10 is usually provided in duplicate for any single installation, there being a unit 10 on each side of the track to simultaneously monitor journal-box temperatures at both ends of the same axle.

Since hot-boxes are primarily a freight car problem, the rolling stock shown in FIG. 1 is a freight car having a main frame 19 overhanging the side frame 20 of one of its trucks, the journal box 18 forming an integral part of the truck structure '20. As best shown in FIGS. 2 and 3, the viewing axis slopes upwardly at an acute angle a, which is preferably of the order of 15 to 50 above the horizontal, and is aligned to observe a part of the journal-box body which projects outwardly of the side frame 20. Very satisfactory results have been obtained when the Viewing angle on is approximately 30 to 50 above the horizontal, said angle being measured in a vertical plane which substantially, but not strictly, parallels the adjacent track 13. Details concerning a preferred viewing aspect are discussed in greater detail in copending application, Serial No. 770,081, filedOictober 28, 1958. g It is to be noted that, since the car frame 19 overhangs the journal box 18, the viewing aspect 16 is such as to establish a more or less uniform and quiet background level for response of cell 14-. In other words, except for intervals between adjacent cars, the viewing axis 16 will either be aligned directly at the underside of the car frame 19 or at a part of the journal box 18.

Thus, for forward-aspect viewing, that is, for a car 19 rolling in a direction toward the detector unit 10 (right to left in the sense of FIG. 1), the image 17 will first intercept the box 18 along the top edge 22 of a first (ie the front) lateral side 23. As the car'proceeds further toward the detector 10, the image 17 scans down a path 24 on the front side 2 3 of the box 18, and (for the box configuration shown) viewing on axis 16 will cover the whole side 23 and most of 'the bottom of the box 18. The important point to note about forwardaspect viewing (that is, viewing the oncoming or forward side of each journal box) is that the cell image 17 moves sharply from the relatively uniform and cool back ground level represented by the underside of the car 19 to the relatively Warm upper edge 22 of the box 18. There is no gradual transition of temperature; on the other hand, the gradient is virtually optimal, inasmuch as the upper part of the journal box is always the warmest part.

For trailing-aspect "viewing, that is, for the situation in which the car 19 is travelling away from the detector 10 (left to right in the sense of FIG. 1), the viewing axis 16 will first intercept the box 18 on its underside, which is always cool relatively to the upper side. Thus, the transition from low background level on the underside of the 'car to 'the level on the bottom of the box '18 will not involve a's greata'rate of change in temperature as for the forward aspect situation described above; nevertheless, the temperature profile along the scanned path will rise suddenly as the image 17 scans up the side 23, and the hottest part of the box will be the last-observed region.

Ordinarily, the cooling effect of onrushing air against the front side of a journal box, as compared with the relatively stagnant air on the rear or trailing side of a journal box, is sutficient to account for a considerable difference in measurable temperature between that at the top of the forward side of the box, as compared with that at the top of the trailing side of the journal box. Thus, it might be argued that best viewing is necessarily for a trailing aspect. This may all very well be true if the train is passing by at sufficient speed so that the detector cell 14 does not become insensitive. However, for slower speeds, system response is definitely degraded (because of low-frequency limitations) if temperature rise in the detector is not fast enough, even though the ultimate total temperature may be fairly substantial.

The above discussion only serves to point out that forward-aspect viewing may be preferred over trailingaspect viewing because the rate of change of measurable heat is greater, even though the maximum observable heat may not be of as great magnitude as that observable with rear-aspect viewing. However, from the standpoint of cleanliness of the lens (i.e. maintenance), trailing-aspect viewing is to be preferred, since the air stream from passing trains tends to sweep dirt away from the lens.

My improved detector is equally applicable to forward or to rear-aspect viewing, but for the case of FIG. 3, rearaspect viewing will be assumed because, in use, cleanliness of the lens proves to be one of the most important factors, and the system can be kept clean for prolonged periods of use in the worst weather. Thus. the car 19 and its wheel 25 will be assumed to be rolling away from the detector unit 10, so that the cell 14 will be subject to the changes in temperature which occur when the image 17 is first intercepted at the underside of the journal box 18.

For the arrangement shown, the cell 14 is employed in a polarized bridge circuit in which a similar cell element 26 is also connected. The element 26 is shielded, as suggested at 27. so as to provide an ambient or reference response against which the transient response of cell 14 may be compared. Bridge output passes first to signalprocessing means including a preamplifier and signal amplifier 28, and for certain applications it is sufficient to directly utilize the signal output of the amplifier 28, as by feeding the same to recorder, alarm, and telemetering means 30-31-32, as needed (alarm means 32 will be understood to function above a preset signalthreshold level representing a safety limit of journal-box temperature. as explained in said copending applications); however, in the preferred form, a gate 33 is employed for the purpose of excluding all heat signals not attributable directly to response of the journal box 18.

The gate 33 may be triggered by a suitable wheel trip, shown only in dotted outline 34 in FIGS. 1 and 2, but described in complete detail in copending applications Serial No. 627,330, filed December 10, 1956, now abandoned, and Serial No. 670,220. filed July 5, 1957. in the names of Cornelius A. Gallagher, et al. For installations employing separate detectors on opposite sides of the track to simultaneously monitor both journal boxes on the same axle, it will be understood that the same trip 34 can serve both detectors 10. It sufiices here to say that the trip 34 may be one of a number of varieties, and in said copending applications the trip 34 comprises merely a magnetic circuit, including a gap which is transiently cut by the flange of the wheel 25. A winding coupled to this magnetic circuit develops the trip signal. Preferably, the Wheel-trip means includes a storage circuit as, for example, a single-stability multivibrator or a time-delay drop-out relay, whereby the trip signal fed to the gate 33 for the purpose of opening the same is of a duration great enough to allow cell response at least to a consistently-defined area representing only exposure to the journal box 18.

The location of the wheel trip 34 with respect to the housing 10 should be such that the gate 33 will open substantially at or just prior to the instant when the cell 14 is imaged on the bottom of the journal box 18, regardless of the speed of the train; this particular situation and instant of time are depicted in FIG. 2. The length of time that the gate 33 remains open should permit viewing at least a consistent part of the passing journal boxes, even for the slowest trains. For example, a gate interval of 50 milliseconds is found adequate even for trains passing at 5 miles an hour. Such a gate in terval is found to present no limitation on detector performance even for the fastest freight trains.

In order to protect the internal parts of the housing 10 during periods when no trains are passing, shutter means 36 is employed to close and open a viewing aperture in the housing 10, the shutter means 36 remaining open as long as a train is passing the detector 10. The wheel trip 34, in conjunction with a relatively long timeconstant storage device 38, may provide the actuating signal for a shutter-opening solenoid 37. Thus, if the time-constant at 38 is long enough to maintain a shutteropening signal to solenoid 37 for the slowest-speed trains, as for example down to 5 miles an hour, the shutter 36 will remain open for all greater-speed trains. When the train passes completely, storage device 38 will fail to excite solenoid 37, and the shutter 36 will close, as by spring or gravity-operated means (not shown), to await the next train. I

The discussion thus far follows generally the disclosure in said copending application Serial No. 620,703 and has been related solely to the problem of detecting hot boxes on trains coming always in the same direction down a given length of track being monitored by the detector 10. However, the device of my invention is automatically responsive to monitor oncoming hot boxes, with the desired viewing aspect, regardless of the direction of trafiic along the track. For example, my detector incorporates automatic means for sensing the direction of oncoming traflic and for selecting the appropriate response aspect in accordance with the sensed direction of trafiic. Also, in accordance with the invention, the same detector cell 14 is so disposed as to serve for viewing passing trains, regardless of the direction of passage.

In the form shown, the same detector cell 14 is served by duplicate optical systems, each of which may be fixed. Thus, for viewing on an oppositely diverging viewing axis 16, a second optical system 15' is employed along with a second shutter 36, duplicating the shutter and optical system for the viewing axis 16, but causing the device to look in the oppositely diverging direction, as through the port 39 (FIG. 1) in the detector housing 10.

In accordance with the invention, the employment of the single cell 14 for selective viewing on one or the other of the axes 16--16', permits employment of the same signal-processing means 28-33 and recording and other display means 3031-32, regardless of the direction of the passing traflic, and the means whereby the direction of traffic is sensed is determined by the order in which the wheel trip 34 and its corresponding trip 34' are actuated. In other words, for trafiic proceeding left to right in the sense of the drawings, the wheel-trip means 34' will be first actuated, that is, before wheel-trip means 34, and a directionally-responsive switch or relay 40 will be actuated to channel subsequent trip signals into one or the other of the storage means 38-38, depending upon the initially detected direction of traffic.

For example, for the assumed direction of traffic proceeding from left to right, the detection of a trip signal at 34' prior to the trip signal at 34, will cause switch 40 to subsequently channel (into the line 41 to storage means 38) only the trip signals developed thereafter by the trip means 34. This particular channelling assumes trailing-aspect viewing, as discussed above. For this assumed direction of trafiic and of viewing aspect, all subsequent trip signals developed by the means 34 will I be ignored by the switch means 40, so that no trip signals will be channelled into line 41' to storage means 38.

The directionally responsive switch 40 preferably incorporates a delayed drop-out feature having a suflicient time-constant to accommodate the lowest train so that, once (for a given train) the switch 40 has selected the channelling direction for subsequent trip pulses, the channel selection will hold for the full passage of the train. It will be noted that even if a train should come to rest on the hot-box detector and subsequently proceed in the same direction, the switch means 40 will be effective to pick up and re-channel correctly for the same direction of traific; thus, when the slow-speed response limit has been passed, in other words, when the train has accelerated say to more than miles an hour, the trip pulses will again be channelled only to the storage means 38.

As noted above, storage means 38 develops a holding signal for actuating the shutter solenoid 37 to assure viewing on the axis 16, as distinguished from the axis 16'. The storage means 38 is shown also supplying a steady signal to relay means 42, thereby rendering relay means 42 directionally responsive to receive and transmit (to the gate 33) only trip pulses fed by line 41 from the wheel trip means 34; thus, as far as the video signal developed by cell 14 is concerned, the recorder and other display means 30-31-32 will see only cell response to journal boxes and not to any other background clutter.

The storage means 38 may provide a still further holding function as long as the train is proceeding fast enough (more than say 5 miles per hour), by actuating enabling means 44 for the recorder and other display means 30-31-32. In other words, when a train first passes the detector in a particular direction sensed by the switch 40, the enabling means 44 will enable or turn on the recording or other display means 30- 31-32. In the case of a recorder, this may take the form of a switch turning on a chart-drive motor, or in the case of telemetering means 32, it may take the form of turning on a carrier-signal generator whereby the video output of the gate 33 may modulate said carrier for remote transmission of the hot-box signal.

From the symmetry of the diagram of FIG. 3, it will be appreciated that for trains proceeding in the opposite direction, that is, from right to left in the sense of the diagram, and for trailing-aspect viewing, the other side of the system will be activated. For example, the trip means 34 will develop a pulse ahead of the trip means 34, so that the directionally-responsive switch 40 will channel subsequent trip pulses into the line 41 to the exclusion of the line 41. Storage means 38' will then be effective to correctly channel the relay 42, and to actuate the solenoid 36 for viewing on the axis 16' to the exclusion of viewing on the axis 16. The enabling means 44 will likewise be activated for the purposes described above.

The arrangement of FIG. 4 illustrates a slight modification of FIGS. 1 and 2 wherein the wheel-trip means 34 embodies two trip devices 50-51 spaced a short distance D apart along the track section 13. The two devices 50-51 are for the purpose of developing separate signals each of which identifies a limit of the operating signal for the gate 33, which may in such case be a doublestability multivibrator. Thus, the trip means 34, embodying the two trip devices 50-51, may include a flip-flop relay or circuit 52 triggered by one pulse to develop a gate-opening signal and by the other pulse to develop a gate-closing signal. By setting the spacing D between the trips 50-51 to correspond with the projected observable width W of a journal box 18, one can be sure that the signal output from the flip-flop circuit 52 is a square gating pulse effective to control the gate 33 during the full period of exposure to the journal box. By inspection of the trigonometry of FIG. 4, the spacing D is preferably at least substantially the journal-box width W, divided by the sine of the elevation angle a of the viewing axis 16.

It will be seen that I have described a relatively simple detector mechanism having improved means for discriminating troublesome hot boxes. With my arrangement, the electronics is simplified by employing a single active detector cell 14 and circuits common to the entire system, regardless of the direction of traflic. The only moving parts are the shutters 36-36, which serve not only to protect the lens systems in the absence of passing trains, but also to select one (to the exclusion of the; other) of the two viewing axes 16-16. My improved viewing aspects provide for the greatest rate of change of observable journal-box signal, regardless of train speeds, for virtually the entire range of train speeds.

While I have described the invention in detail for the preferred forms shown, it will be understood that modi fications may be made within the scope of the invention as defined in the claim which follows.

I claim:

In combination, a length of railroad track accommodating alternately and from time to time trafllc proceeding in each of two opposing directions, and an infra red hot-box detecting device comprising a housing fixedly mounted alongside one of the rails of said track and below the level of passing journal boxes; said housing containing an infra-red radiation detector element producing an electrical signal in response to incident radiant energy, two separate optical systems within said housing, the first of said optical systems comprising an opening in said housing and fixed optical means in direct alignment with said detector element and oriented to continuously image said detector element through said open ing on a first upwardly sloping axis and in a first general longitudinal direction along the track with the detector element imaged at substantially the plane of passing journal boxes, the second optical system including a second opening in said housing and fixed optical means in direct alignment with said detector element and oriented to continuously image said detector element through said second opening and on a second upwardly sloping axis directed generally in the opposite longitudinal direction of the track, each of said optical systems including a shutter device and separate actuating means therefor, means normally closing both said shutter devices, and actuating means including means responsive to the direction of passage of a train on said track in the vicinity of said detector and connected to open one of said shutter devices to the exclusion of the other in response to a detected first direction of train movement, said last-defined means being further responsive to detected train move ment in the opposite direction to open the other of said shutter devices to the exclusion of said one, whereby a said single detector element may respond with a desired consistent viewing aspect on all passing vehicles regardless of the direction of train movement past said detecting device.

References Cited in the file of this patent UNITED STATES PATENTS 2,818,508 Johans'on et al. Dec. 31, 1957 2,856,539 Orthuber et al. Oct. 14, 1958 2,856,540 Warshaw Oct. 14, 1958 2,880,309 Gallagher et al. Mar. 31, 1959 2,906,885 Orthuber et al. Sept. 29, 1959v 

